Lens-grinding machine



Dec. 23, 1924. 1,520,094

. L G. SIMPSON LENS GRINDING MACHINE Filed Nov, 30, 1918 ulmmulu llllllllllllfillIlllllllllllllllllllllll lllllllllllillll IIIEIIIIZZsATTORNEYS Z9 INVETNJ'OR w Z6072 lfim as'orz I 9 BY I v.

Patented Dec. 23, 1924.

LEON Gr. SIMPSON, OF ROCHESTER, NEW YORK, ASSIGNOR TO BAUSGH & LOMBOPTICAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

LENS-GRINDING- MACHINE.

Application filed November 30, 1918. Serial No. 264,851.

- citizen of the United States, residing at Rochester, in the county ofMonroe and State of New York, have invented certain new and usefulImprovements in Lens- Grinding Machines; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

My invention relates to lens grinding 1nachines, and more particularlyto that class of machines in which a lens blank is mounted on a lenscarrier and rotated in contact with an abrading lap which is alsorotated. The object of my invention is to provlde an improved adjustablethrow crank for reciprocating the lens blank on the grinding lap duringthe grinding operation and which can be accurately adjusted for lensesand laps of different diameters. A further object of my invention is toprovide an adjustable throw crank which is held in adjusted position bymeans of a friction clutch and which is easily adjusted by means of afinger piece.

In the drawings:

Fig. 1 is a front elevation of a portion of a lens grinding machineembodying one form of my invention, parts being broken away to exposethe underlying parts;

Fig. 2 is a plan view of the overthrow crank with connected partsdetached from the machine Fig. 3 is an enlarged section on the line 2 -2of Fig. 2;

Fig. 4: is a section on line 4 9 of Fig. 3 somewhat reduced;

Fig. -5 is a perspective view of'a friction plaite forming a part of myconstruction, an

Fig. 6 is a plan view of the scale and cooperating pointer, parts beingsectioned away for clearness.

Similar reference characters refer to the same parts in all the views ofthe drawings.

I have shown my invention applied to a lens grinding machine whichcomprises a table or support 1 in which is rotatably supported a shaft 2extending upwardly through the table and driven by any suitable sourceof power, not shown herein. A lens grinding or abrading lap or polishingshell 3 is detachably supported on the upper end of the shaft 2. Thisconstruction permits a lap or shell to be substituted for one in themachine when lenses of difierent diameters or curvature are to beground. Cooperating with the lap 3 is a lens block or carrier 4 to whicha lens blank 5 to be polished or ground is secured by means of cement orsuitable plastic material. The lens carrier is detachably connected witha lens carrying shaft or spindle 6 which is journaled in an overhangingarm 7. The overhanging arm 7 is pivoted'in a yoke 8 permitting it toswing upwardly in a vertical plane to raise the lens carrier from thegrinding lap and at its outer end may be provided with a handle 9 bywhich it may be manipulated. The yoke or bracket 8 is secured to a post10 mounted on a support 11 on the table 1. At its upper end and Withinthe hollow overhanging arm 7 the shaft 6 is provided operativelyconnected by means of a belt or noiseless chain with a similar pulley orsprocket wheel on the upper end of a shaft or spindle 12-rotatablysupported in the table 1 and extending upwardly therefrom through thehollow post 10 and its support 11. At its lower end and beneaththe table1, the shaft 12 has a sprocket 13 secured thereto by which the shaft isdriven by means of a noiseless chain 14 which connects the sprocket witha sprocket 15 secured to the shaft 2. The support 11 is adjustablysecured to the post 10 by means of a clamp, 16 and has a bearing on theupper surface of the table 1.

Secured to the shaft 12 is a pinion or gear wheel 17 which meshes with agear 18 keyed to the end of a shaft 20, which has a bearing in thetable 1. To the upper end of the shaft 20 is secured an adjustable throwcrank device comprising a clutch member 21 provided with a plurality ofopenings or rec'esses 22 in its upper surface six being shown in theformillustrated. Seated in each of the recesses 22 is an expansion coilspring 23 which projects above the upper surface of the member 21, andengages a friction plate 24;. The plate 24 is provided with, a pair ofprojections or lugs 25 which are seated in a pair of recesses 26 in theclutch member 21 and prevent relative rotary movement between the plateand clutch member. The

75 with a pulley or sprocket wheel which is I clutch member 21 is seatedin a cooperating clutch member 27 in the form of a cup and having a ring28 secured to its open end by means of screws 29 and serves to hold orre tain the cup member in operative position on the member 21. Seated intapped openings in the wall of the cup member 27 is a pair of set screws30 which are adapted to frictionally engage the plate 24. By adjustingthe set screws 30 the tension of the springs 23 may be varied which inturn changes the pressure on the friction surfaces between the setscrews 30 and the plate 24 and also between the ring 28 and clutchmember 21. The clutch member 21 is mounted eccentrically of the shaft 20and the clutch member 27 is formed eccentrically of the end of anupwardly extending shaft 31 having a finger piece or handle 32 keyed orotherwise secured thereto at its upper end. A, sleeve or element 38 isjournaled on the shaft 31 between the member 27 and the finger piece 32and has an internally threaded boss 3st projecting from one sidethereof. A connection in the form of a screw 35 is threaded in the boss34 and into a boss 36 formed on a sleeve 37 which has a bearing on apost 38 provided therefor on an outwardly projecting bracket 39 formedon the sleeve 11.

In operation, the shaft 20 is rotated through the gears 17 and 18 whichmotion is transmitted through the clutch devices to the member 27, whichimparts an axial reciprocatory motion to the screw 35 to reciprocate thesleeve 10. The construction is such that the movement of the sleeve orpost 10 serves to reciprocate the overhanging arm 7 to move the lensblank back and forth over the surface of the grinding lap. By turningthe clutch member 27 to vary the eccentricity of the shaft 31 relativelyto the shaft 20, the extent of movement or throw of the lens carrierrelatively to the grinding lap is also varied, thus adapting the throwof the lens carrier to grinding laps of different diameters and adaptingthe machine for grinding lenses of different diameters. By releasing theclamp 16, the connection between the members 11 and 10 is broken,permitting the member 11 to reciprocate independently of the member 10and thus rendering the adjustable throw crank devices inoperative.

In order to facilitate adjustment of the crank for different grindinglaps or lenses of different diameters, a pointer 12 may be secured tothe clutch member 21 which extends outwardly, upwardly and inwardly tocooperate with a suitable scale 13 on the up per surface of the member27. The screw 35 may be provided with a knurled finger piece 44 wherebythe screw may be turned to properly' center the lens carrier on thegrindinglap. In order to prevent the formation of striations in thegrinding of the lens due to variations in the hardness and sizes of theparticles of the abrasive material, the gears 17 and 18 are formed ofsuch sizes that in all positions of adjustment of the adjustable crank,the surface relations between lens carrier and grinding lap areconstantly changed so that a large hard particle will not retrace itspath on the lens blank causing the formation of striations.

While the invention has been disclosed embodied in a machine having thelens carried by the reciprocating member, it will be un derstood thatthe invention is also adapted to those machines in which the grindinglap is reciprocated or in which the grinding lap is located above thelens carrier, since such variations in arrangement of parts are old andwell recognized in the art.

Having described my invention what I claim and desire to secure byLetters Patent 1. In a lens grinding machine, the combination with alens carried and a grinding tool one of which parts has a to and fromovement relative to the other, of driving means, a clutch disk rotatedeccentrically by said means, a second clutch disk in adjustablefrictionally driven engagement with said first disk, and means connectedwith the movable one of said parts eccentrically connected with saidsecond disk for elfectingsaid to and fro move ment, said disks beingadjustable relative to each other to vary the amplitude of said to andfro movement.

2. In a lens grinding machine, the combination with a lens carrier and agrinding tool, one of said parts having a to and fro movement relativeto the other, of

mechanism for driving said movable part comprising an eccentricallyrotated, substantially disk-shaped member, a second member provided withbearing means disposed eccentrically thereof, and adjustable springactuated means yieldably connecting said members to provide fortransmission of driving force and for adjustment of one of said membersrelative to the other to vary the amplitude of movement of said movablepart. 7

3. In a lens grinding machine, the combination with a lens carrier and agrinding tool, one of said parts having a to an fro movement relative tothe other, of mechanism for driving said movable part comprising aneccentrically rotated member, a second substantially disk-shaped memberhaving peripheral means for rotatably embracing opposite sides of thefirst member and having also an eccentrically disposed bearing means,adjustable spring actuated means yieldably connecting said members toprovide for the transmission of driving force and for relativeadjustment of said members to vary the throw of said bearing means, andmeans adjustably connecting said bearing means and said movable part.

4. In a lens grinding machine, the combination with a lens carrier and agrinding tool, one of said parts having a to and fro movement relativeto the other, of mechanism for driving said movable part comprising apair of disks, one having means for rotating the same eccentrically andthe other having an eccentric element, adjustable frictional meansyieldably connecting said disks to provide for transmission of drivingforce and for relative adjustment thereof to vary the throw of saidelement and adjustable link means releasably connecting said element andsaid movable part.

5. In a lens grinding machine, the combination with a lens carrier and agrinding tool, one of said parts having a to and fro movement relativeto the other, of mechanism for driving said movable part comprising aneccentrically rotated, substantially disk-shaped member, a secondsubstantially disk-shaped member provided with eccentric bearing meansand with peripheral means for rotatably embracing opposite sides of saidfirst member, a substantially plate-like means rotating with one of saidmembers and spring pressed toward the other, adjustable contact means onthe other member for yielding engagement with said plate to transmitdriving force and provide for relative adjustment of said members tovary the throw of said bearing means, and a connection between saidbearing means and said movable part.

LEON G. SIMPSON.

